Selective signaling apparatus.



No. 568,967.- Patnted Feb. 26, 1901.:

.1. A. BARRETT. SELECTIVE SIGNALING APPARATUS. (Application filed Sept.20, 1900.! (No llodel.)

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No. 668,967. Patentad Feb. 26, I901.

J. A. BARRETT.

SELECTIVE SIGNALING APPARATUS. (Application filed Sept. 20, 1900.! (NoModal.) 3 Sheets-Sheet 2.

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SELECTIVE SIGNALING APPARATUS. (Application filed Supt; 20, 1000') (NoModel.)

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e 3 V k tlsrtTnn STATES PATENT OFFICE JOHN A. BARRETT, OF SUMMIT, NEWJERSEY, ASSIGNOR TO THE AMERICAN TELEPHONE AND TELEGRAPH COMPANY, OF NEWYORK.

SELECTIVE SIGNALING APPARATUS.

SEEGIETQATION forming part of Letters Patent No. 668,967, dated February26, i961.

Application filed $eptember 20, 1900. Serial No. 30,590. (No model.) I

To all it W 00716677 only. The bell will not ring with similarcur- Be itknown that I, JOHN A. BARRETT, rerents in both ringing and retainingmagnets siding at Summit, in the county of Union and when arranged inseries. The bell will not State of New Jersey, have invented certainring with similarcurrents in both ringing and 5 Improvements inSelective Signaling Appararetaining magnets when arranged in parallel.tus, of which the following is a specification. In the drawings whichaccompanythis speci- Thisinvention relates to the selectiveoperafication, Figure l is a perspective view of an tion of the severalcall-bells of a polystation electromagnetic bell exemplifying theessentelephonecircuit extending outward from a tial principles of myinvention. Fig. 2 is a to central station to a plurality of substations,diagram representing conventionally a teleand more particularly concernsselective bells phone-exchange circuit extending from a cento beoperated by alternating currents on tral station to four substations andprovided main circuits extending betweenacentral and at each of the saidsubstations with selective four sub stations. bells containing theinvention. Fig. 3 is a 15 The object of the invention is to provide atop or plan viewof a practical form of my system of telephone-stationbells perfectly electromagnetic selective bell. Fig. 4 is a adapted forselective operationon a line havside elevation of the same. Fig. 5 is adeing four substations, the bells of all of the tail view of thepole-pieces and armatures of stations being simple and substantiallyunithe ringing and retaining magnets. Fig. 6 is 20 form in structure andhaving their selectivity a diagrammatic view of the circuitarrangedetermined by differencesin the arrangement ments at thesubstations, showing particuof their magnet-windings, in the mode ofconlarly the winding of the electromagnets. necting the said windingswith the main cir- Referring now to Fig. 1, M is the ringingcuit, and inthe mode of transmitting the electromagnet, and its core 0 is attachedat 25 ringing-current through the main circuit. In its lower end to theiron plate P, which thus the attain ment of this object I provide forconstitutes a portion of the magnetic circuit. each bell apparatus twoelectromagnets, both The upper end of the said core is extended havingarmatures attached to the bell-hambeyond the spool and is slotted orforked vermer, one of the said magnets being arranged tically. A is asoft-iron armature having 0 to operate the said bell-hammer, while theone end within the slot of said magnet-pole other is arranged undercertain conditions to and hung on pivots p p in a vertical plane,maintain the quiescence thereof. The first of so that its other end iscapable of a lateral these may be termed the ringing magnet motion only.To the free end of the armaand the second the retaining or locking turethe rod R, carrying the bell-hammer h, 5 magnet. The ringing-magnetorits armature is secured, the said bell-hammer being, as is polarized;but the retaining-magnet and shown mounted between the gongs or bellsits armature are both neutral or non-polarb b. A permanent U-magnet m isfastened ized. Then these two electromagnets are to the iron base-plateP, and its limbs extend wound with an equal number of turns to anupwardly, one at each side of the armature 9o 40 equal resistance, andalternating currents, A. This appliance so far as it has been desuch asare used in magnetobell ringing, are scribed thus constitutes asimply-constructed passed simultaneously through the windings polarizedelectromagnetic bell which I have of both, either in series or multiple,the refound highly efficient and satisfactory in optaming powerofLhelocking-magnet is greater eration. If alternating currents are caused5 5 than the motive power of the ringing-magnet to traverse the windingof the electromagnetand no movement of the armature of the lat- M, acorresponding lateral vibration or oscilter occurs. From thisexperimental fact I lation between the poles of the permanent deduce thefollowing fourcorollaries:The bell magnet m will be imparted to the freeend will ring with alternating currents in the of the pivot-ed armatureA, and such oscilla- 50 ringing-magnet only. The bell will not ring tionbeing participated in by the bell-hamwith similar currents in theretaining-magnet mer the bell is rung. To secure the selectivity of sucha bell, I associate with it a second electromagnet N and its U-shapedarmature a. The electromagnet N is fastened by the lower end of its coreto the plate P which is preferably of soft iron, but separated by anair-space from the larger plate P. The upper end of the core is extendedto form the pole-piece 0 The armature a is rigidly attached by an arm1', of brass or like material, to the armature A in such wise that itstwo limbs are steadily supported in a position where they bestride thepole-piece 0 The extent of separation between the limbs of the armaturea conforms to the working adjustment of the armature A and is such as topermit the proper oscillatory movement of the latter and to serve as alimiting-stop to such movements in both directions.

When the apparatus is not working, the

armature A under the influence of the permanent magnetm rests indifferently on either side, one limb of the armature a, for instance, beingpressed against the pole 0 while the other limb of said armature will beseparated from the pole-piece by a space equal to the amount of lateralmovement desired and provided for. Under these conditions an electricalcurrent circulating in the windings of the electromagnet N will tend tohold the limb of the armature a, in its normal position with respect tothe pole-piece c and if the current in the coils of N be strong enoughthe said magnet N, serving as a locking or retaining magnet, willprevent the operation of the ringing-magnet M, even though analternating current of otherwise appropriate strength and character wereflowing through its winding, as well as through the coils of the magnetN. It thus follows that if four such bell mechanisms are connected withthe same circuit any one of the four can be operated to the exclusion ofthe others by pro-, viding that in the bell to be rung the r in g-.ing-current shall excite the ringing-magnet only and that in the bellswhich are not to be rung either the retaining-magnet alone or bothmagnets shall be excited.

In Figs. 3, 4, and 5 is shown a form of mech: anism containing equallywith Fig. l. the ele-. ments of my invention, but better adaptedstructurally for practical use. M is the ring? ing-magnet, having twopole-pieces c c, and A its polarized armature, pivoted at 1919 andadapted to oscillate in front of and between the said pole-pieces. Thepolarizing-magnet min this form of apparatus is at its pole n screwedinto position immediately behindthe center of the armature A, and themagnet itself is so bent or curved as to bring its other pole s oppositethe middle part of the ringing-magnet M. When thus secured, the magneticflux from the pole s is across the wirespace of the spool of magnet M tothe core thereof and thence in both directions through the said core andthe pole-pieces c to the armature A and the other pole n of thepolarizing-magnet m. V is a plate, of brass or similar material, forminga base-plate for the entire structure, and extending rearwardlytherefrom are two brass posts o '0 formed into screws at theirprojecting ends. The reverse or heel ends of the pole-pieces c areturned outward to form the supporting-lugs 1; 21, are perforated so asto slide over the screw ends of the posts 111. and are clamped eachbetween two nuts upon the screwposts. Near the outer ends of thepostsoand clamped at each end thereto is the metal yoke m, and an ironangle-piece 9 supports in its lugs the pivots of the armature A. Thescrew 3 passes through a hole in the center of the yoke 00 and through aslot in the end of the permanent magnet m and screws into theangle-piece g, thus clamping the magnet, yoke, and angle-piece firmlytogether, and this arrangement forms a combined mounting for thepolarizing-magnet and the armature Ain such a relation to theringing-electromagnet M that the said armature A overlaps by its endsthe extremities of the polepieces a c. A polarized electromagneticmovement simple in structure and of high elliciency, having, moreover,only a single magnet-spool and capable of all necessary adjustments, isthus constituted. The yoke 00 may be raised or lowered on the posts '0,increasing or diminishing, as required, the width of the air-spacebetween the armature A and the pole-pieces c, or the spool of theelectromagnet M may be raised or lowered on the screw-posts with thesame effect, or one end of the spool of said magnet may be raised orlowered with respect to the other end, producing at will either abalanced or a biased relation between the armature A and the pole-piecesc. The rod or arm R, attached to or actuated by the armature andprovided at its other end with the bell-hammer h between the gongs b,completes an advantageous form of polarized ringer. Theretaining-electromagnet N, on which are based the selectivecharacteristics of the apparatus, is secured at one end to the frontplate V and has two angular pole-pieces 0 0 which, attached by one oftheir ends to the ends, respectively, of the magnet-core, are bent overthe side of the magnet, as best shown in Fig. 4, and are slotted orforked at their extremities, as indicated more particularly in Fig. 3.The said pole-pieces c overlap their magnet-spool on the side facing theringing mechanism and the slots of the twopole-pieces are in line witheach other.

Upon the armature A of the ringing-magnet M is rigidly lixed the bentaluminium mechanical connection or plate R which is projected forwardlyand carries the armature d of the retaining-magnet, extending beyond thesame and being turned up into a foot for the more convenient attachmentof the bellhammer proper, R. The said retaining-magnet armature forms amagnetic bridge between the pole-pieces c nearly filling up the gapbetween them. It has a small lateral movement within the slotscorresponding to the oscillations of the ringing-armature A, whichoscillations in turn, as also the length of the bell-hammer stroke, arelimited by the difference between the thickness of the armature a andthe width of the slots in the polepieces a. The blade-armature a ofFigs. 3, at, and 5 is identical in function with the U- shaped armaturea of Fig. 1, and, in fact, is the same device.

The apparatus as a whole is responsive to the passage of electricalcurrents through its coils exactly as is the form of Fig. 1. Ifalternating ringing-currents are sent through magnet M only, thepolarized armature A is thrown into oscillation and the bell is rung;but if the currents are divided equally and simultaneously between thewindings of the ringing and the retaining magnet the armature a, of thelatter is retained at that side of the slots where it initially restsand the bell does not ring. It is to be noted that both slots in thepole-pieces c are of the same Width; but from the fact that the slot inone pole-piece is located at a greater radius from the pivot p19 of thearmature A than the slot in the other pole -piece the armature aactually strikes the sides of the slot only at the end farthest removedfrom the pivot, a slight gap remaining on either side at the nearer endof the armature. This does not adversely afiect the operation of themechanism and is,in fact, an advantage, since it shows that the saidoperation is not in any sense dependent on exact adjustments.

A circuit arrangement for a metallic telephone-circuit extending from acentral station to four substations and fitted at each with one of mybell mechanisms organized for selective operation, together withcorresponding signaling-keys, one for the bell of each substation,adapted, respectively, to transmit the appropriate current over theappropriate conductor combination, is illustrated in Fig. 2. L is themetallic substation telephonecircuit extending between a central station0 and a plurality of substations, at each of which are the usualtelephones, switches, and call apparatus. In the drawings the telephonesand switch apparatus are indicated at one only of the substations-viz.,Q but it is to be understood that at all of the stations the telephonesare placed and connected as usual. As shown, the telephone is connectedin a normally open bridge 80f the line controlled by the gravity-switchw. H and I are the two main conductors of the circuit. B at eachsubstation indicates the entire bell apparatus. K, K K and K are keys atthe central station corresponding to the substation bell mechanisms,respectively. S is a source of alternating call-currents supplyingcurrent to the main circuit-conductors when three of the keys aremanipulated. S is a second source of like character, whose connectionwith the said conductors is controlled through a fourth key, and Eindicates the several earth connections.

The winding of the electromagnets at the several substations can' bebest understood from Fig. (5 of the drawings. At station Q theelectromagnets M and N each have a single winding, and these areconnected with the circuit in such a way that the winding M is placedbetween the main conductor H and the station earth connection E, and thewind ing of N is included between the conductor I and the said earthconnection. At the second station Q also each of the magnets has but asingle winding connected between its main conductors,respectively, andthe ground connection. At substation Q both of the magnets M and N havetwo equal windings, and these are so connected that for currentstraversing the metallic circuit outward over one of the main conductorsand inward over the other, so that the two conductors are in series,their effect in magnet M coincides or is cumulative and in magnet N isreciprocally or mutually neutralizing, and at station Q l each of thetwo magnets has two equal windings so connected that for currentstraversing the main conductors H and I in parallel the eifect in magnetM is cumulative or reinforcing and in magnet N is reciprocallyneutralizing.

The central sources S and S of calling-current are shown as beingalternating-current generators. The source S is grounded at one terminaland united at the other to a busconductor Z, having branch conductors30, 31, and 32, branching, respectively, into the signal-transmittingkeys K, K and K and connected in said keys to the terminalcontact-springs z. The source S is not grounded, but has both of itspoles connected with the key K one pole being united by conductor to theterminal contact-spring z and the other by conductor 34 with the spring2 A branch from main conductor H extends to the line contact-spring a:in the key K and a similar branch from main conductor I to thecontact-spring 00 in the key K the said springs being each mounted insuch relation to the current contact-springs z that when a key ismanipulated contact is established between the contact-springs x and 2thereof. Branches extend from both main conductors into key K andconnect therein with line contactsprings 00 00 and in this case theoperation of the key will bring both of the said line-springs intocontact with the springs z and 2 connected with the source S Into key Kalso there extend branches from both main conductors, and they end inthe contact-springs a; J0 of said key. When, however,this key ispressed, both line-terminal springs are brought into electricalconnection with the single-source terminalzof the groundedcall-generators. It is now evident that the operation of key K willtransmit alternating currents over main conductor H only, that theoperation of key K will transmit alternating currents over mainconductor I only, that if key K be depressed the source S will beintroduced directly into the metallic circuit L and will transmitcurrent over the two main conductors in series, using one as theoutgoing and the other as the return conductor, and that themanipulation of key K unites the two main conductors H and I in paralleland connects both to the source S. With structure and circuits thusdescribed if alternating currents are sent as from key K on line H toground the bell at station Q will be rung, because these currents Willpass at that station through the M or ringing magnet only. The currentswill pass through the retaining-magnet N only at station Q and throughone-half of M and N in series at the third and fourth stations.Consequently the second, third, and fourth bells will not ring with keyK. In like manner key K which sends currents on line I to ground, willring the bell at station Q only. Key No. 3 sends currents across thecircuit between line H and line I. These currents will not ring thebells at stations Q and Q because they pass through both magnets inseries. They will ring the bell at Q because their efiect is cumulativein M and neutralized in N, and they will not ring Q because their effectis neutralized in M. Key K sends currents on line H and line I inparallel to ground. These currents will not ring the bells of stations Qand Q because they pass through M and N in multiple at these stations.They will not ring the bell at station Q because their effeet isneutralized in M. They Will ring the bell at Q, because their effect iscumulative in M and neutralized in N.

It is to be observed, although for the sake of clearness I have showntwo sources S and S of alternating current at the central station, thatone source only in practice may.

...tions to the line work efficiently and Without special adjustmentover a wide range of line resistance, and from the fact that the bellsare rung by alternatin gcurren ts the bells are operative throughcondensers at the stations, and the system is therefore exceptionallyWell adapted for use in association with the four station-circuits of acentral-battery exchange.

I claim-- 1. In aselective signaling system for a fourstationtelephone-exchange circuit, the combination with the two main conductorsof said circuit extending between a central station and the said foursubstations; asouree of alternating current at said central station; andfour keysat said central station organized to connect the said sourcewith the said main conductors separately, with both in series, and withboth in parallel; of four electromagnetic bll mechanisms correspondingand responsive each to a different one of the said keys, and placed oneat each substation, each bell mechanism comprising a polarizedringingeelectromagnet having an armature carrying the bell-hammer, and anon-polarized retaining-electromagnet having an armature also attachedto said bell-hammer, the two magnets of the several bell mechanismsbeing diversely connected in relation to the said main conductors insuch manner that the circuit of the central source completed by any keyshall actively include the winding of the ringing-magnet alone in thebell mechanism corresponding to such key, and the winding of theretaining-magnet in the others; substantially as set forth.

2. A selective electromagnetic bell mechanism for the substations of apol'ystation telephone-exchange circuit, comprising a polarizedactuating-electromagnet, an oscillatory armature therefor,a bell-ham mercarried or actuated by said armature, and adapted to strike a gong orother sounding medium, a neutral retaining or looking electromagnet, andan armature therefor associated with the bell-hammer rod; the said twoelectroinagnets having windings and resistance of like magnitudes, andthe said bell mechanism being responsive to an alternating electricalcurrent exciting the polarized magnet only, but irresponsive to asimilar alternating current exciting both magnets, or the neutral magnetalone; substantially as hereinbefore described.

3. The combination in a selective electromagnetic bell apparatus for thesubstations of a telephone-exchange circuit, with a polarized bellcomprisinga polarized actuating or ringing electromagnet withoverlapping and approximating pole-pieces, a centrallypivoted armaturetherefor, a gong or sounding medium, a bell-hammer carried by a rod andadapted to strike said gong, a rigid mechanical connection uniting thesaid armature and bell-hammer rod, a polarizing perlnanent magnetdetermining opposite normal polarities to said magnet-poles andarmature, asupporting-frame for the said magnets and armature, and meansfor their relative adjustmentassociated with said frame; of means forrendering the said bell selective, consisting of a non-polarizedretaining-electromagnet, having a winding and resistance similar tothose of the actuating-magnet, pole-pieces therefor overlapping its sideand approaching one another in a plane parallel to that of thebell-hammer and its mechanical connection the said pole-pieces havingslots in line with each other in their ends, an armature thereformounted on the said mechanical connection, having its ends Within thesaid slots, and forming a continuation of the magnetic circuit of thesaid slotted pole-pieces; wherename to this specification, in thepresence of by the bell may be rung when the ringingtwo subscribingwitnesses, this 4th day of magnetalone is excited, and maintained qui-September, 1900. escent when both magnets or the retaining- JOHN A.BARRETT. 5 magnet alone is excited; substantially as and Witnesses:

for the purposes specified. GEO. WILLIS PIERCE,

In testimony whereof I have signed my JOSEPH A. GATELY.

